'24 Ram Hemi less power than '17 Hemi?

[HSKR R/T]

At 80, the difference is 489 rpms. 3.92 is at 2700 rpms, 3.21 is at 2211.

The difference will be more if there are different diameter tires with each gear as well.

 

[dajogejr]

Again…. Math is one thing.
Variables is another.
One is worthless without having the other.

Throwing out more math without having the proper variable, like tire diameter, is just more incorrect information.
You are assuming tire diameter is 32” for both size rims/tires.
Clearly, it’s not. More data using that same variable clearly, isn’t correct.

Respectfully silver, you can’t tell me the difference if the variables aren’t correct.

 

[silver billet]

Again…. Math is one thing.
Variables is another.
One is worthless without having the other.

Throwing out more math without having the proper variable, like tire diameter, is just more incorrect information.
You are assuming tire diameter is 32” for both size rims/tires.
Clearly, it’s not. More data using that same variable clearly, isn’t correct.

Respectfully silver, you can’t tell me the difference if the variables aren’t correct.

I double checked and I was using 7th gear for comparisons in both trucks instead of 8th. That's my bad. Here are updated numbers, also using as much accurate information as I can find WRT tire sizes and transmission ratios.

TL;DR: you got pretty close to nailing the actual RPMs in both trucks, but being a little bit off in spots means the difference in RPMs between the 2 trucks is less than you think.


Tire sizes:
new truck: 285/45/22 = 32.1
old truck: 275/60/20 = 33

Transmission ratios (8th gear)
new truck: 0.64
old truck: 0.67

Axle ratios
new truck: 3.21
old truck: 3.92

new truck at 65 mph:
= (65 * 3.21 * 0.64 * 336) / 32.1
= 1397

old truck at 65 mph:
= (65 * 3.92 * 0.67 * 336) / 33
= 1738

Difference at 65 mph = 340
Difference at 70 mph = 366
Difference at 80 mph = 419

RPMs at 65 mph
new truck = 1397
old truck = 1738

RPMs at 80 mph
new truck = 1720
old truck = 2139